I moved back in with my parents after undergrad, since my grad program is close to their house. It's been great not having to pay rent, but having that independence taken away and feeling almost like a kid again isn't the best feeling.
I think when you are financially ready, to the point where you have enough in savings to cover a few months rent--should you ever lose your job or something unexpected happens--they you can think of making that big jump to independence. Freedom is of course pricey, but once you are settled into your post grad job, it will be worth it to get away. Just make sure that you move out with roommates that you trust and who will add to your independence, not hinder it.

It honestly really depends on what your situation is. My sister moved out right away, but only because she had a stable job and enough money to start paying rent. However, for people who are going immediately to graduate school, it's not necessary to move out right away because you never know where graduate school may take you. If you are going to graduate school, look into short-term housing but have your permanent address be your parent's home address.
If you can't find housing right out of college, there is no shame in living with your parents until you have your plans figured out (you save money and you get to sleep in your cozy bed). You shouldn't move out unless you have a stable job and can pay rent.

I have found that since creating my own life and getting used to my own independence, it's tough for me to live with my parents. I think as soon as you feel financially able to keep yourself afloat, it's time to move to your own place. It's not worth feeling so overwhelmed that you can't keep up with your bills, but it's definitely worth it.

There is no specific age or deadline. It's a very ambiguous situation, in that you won't know until the time is right.

Basically, moving back in with your parents is an opportunity to get on your feet, make a little money for your savings and prepare to really enter the real world. For some, this could take 2 years. For others, this is only going to take about 6 months.

This is a case by case situation, so have that conversation with your parents. You don't want to be a burden on them longer than you have to, but you also don't want to put yourself into debt by leaving earlier than you were ready to. It's best to sit down with them and discuss your plans, and you can both set up a timeline that will work for all parties involved.